Clamp arrangements including a nut and bolt, and at least one shaped clamp head are utilised to attach items to a structural steelwork element, or to connect two structural steel work elements to one another. Typically, the distance from an engagement surface of the clamp head to a reference plane must be measured or calculated, and the size of the clamp head chosen must be able to accommodate the desired distance. Failure to correctly calculate or measure the distance, or to ignore this requirement in its entirety, can lead to the use of a clamp head, clamp or clamp and packer combination which is not suitable for the job in hand.
EP 1946891 is an earlier application belonging to the present applicant and discloses a clamp head having an arched body and opposing unequal length arms. The arms define a reaction arm having a curved reaction face and a clamping arm having a curved clamping face. The curve of the reaction face has a constant radius, and the reaction face is further provided with ribs extending fully across its width. EP 0431209 discloses a clamp head configured for use with profile rail. The reaction arm of the clamp head is provided with a lip on either side of the reaction face. The lips cooperate to locate the clamp head on the profile rail and to prevent rotation of the clamp head relative to the profile rail. DE 2816295 discloses a machine tool clamp having a reaction arm that is significantly longer than the clamping arm. This clamp is susceptible to weakening or cracking of the reaction arm at elevated loads.